There is a long felt need for an illumination light system that can be worn while a person runs. As used herein, an illumination light is a light that produces a directed beam of light to illuminate an object so that said object is visible to a person. FIG. 1 is an illustration of a prior art illumination light system 100 worn by a runner 108. This figure is based on FIG. 1 of U.S. Pat. No. 7,828,455 (Barker). The illumination light system comprises a chest strap 102 worn around a runner's torso 106. An illumination light 104 is mounted on the chest strap and is directed forward and downward to project a beam of light 112 on a path 114 in front of the runner. The illumination light is directed in the sense that the divergence angle 122 of the light beam is relatively small. A divergence angle of 90 degrees or less is considered small.
One of the limitations of the prior art illumination light system is that it can slip down 118 on the runner's torso due to the pounding of the runner's feet. There is need, therefore, for an illumination light system that can keep an illumination light on a person's torso when they run.